This invention relates to improved data storage tape assemblies. Configurations reducing the average time-to-access data under conditions of load are disclosed.
Computer, audio, and video systems typically require a means of storing large volumes of information (analog and digital). Magnetic tape drives packaged as individual units or packaged as a part of an automated tape library system have been one means for storing this information. Optical tape drives have also been used. Within an automated tape library, mechanisms are provided for sequentially: a) moving a stored tape to one of the provided tape drives (or moving the tape and the tape drive); b) loading the tape; c) advancing the tape to the desired location; d) reading or writing data; e) returning the tape to the starting position; f) unloading the tape; g) and returning the tape to it's storage location. Larger automated tape libraries may provide multiple mechanisms, but even with multiple mechanisms, the operations remain essentially sequential. Overall system performance is a function of the capabilities of the tape movement mechanisms, the loading mechanisms, tape technology, speed of the tape drive, tape length, size of the information to be handled, and location of the information on the tape. Many of today's production systems can take several minutes to complete a full tape operation commencing with picking the tape out of storage and concluding with the return of the tape to a storage location. One product utilizes self-contained tape cartridges with a simple magazine structure to achieve an advertised tape load time of 4 seconds and an average access time of 8 seconds (1/4 tape length), for a combined average time-to-data of 12 seconds and an average cycle-time (return tape to starting location) of 20 seconds.
While the prior art has recognized the value of a wide range of design features, those properties may be utilized in combination and in select configurations to: a) enable almost instantaneous (hard disc like delays) access to initial data fragments of a stored information object; b) reduce time-to-data under all conditions; c) increase parallel operations within each logical operation; d) further reduce time-to-data under conditions within which multiple operations are queued; e) reduce overall system costs; and f) further increase physical storage density.